How to get through this? By bringing it to light and exploring it with your T.

You cannot 'solve' this riddle by yourself primarily because what you feel is in relation to another human being i.e. your T. It is relational and your T is part of the equation. Hence, your T ought to be invited (by you) to explore why you feel this, is there a pattern in your life about letting people in and being burnt, what do you get by keeping people out, what is the fear, have you been rejected or abandoned before etc. etc.

It is not so much about solving anything (how would that be possible anyway). Sadly, things end in one form or another. This is inevitable. But it is possible to come to terms with endings and letting other people in regardless. This could be the work in therapy.